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Group I
__FORCETOC__ The Basics It's expected that you'll remember the basic Chemistry of Group I from GCSE but you don't need to know any new reactions, you just need to explain what you learned in a little more detail. Group I elements are very reactive and you should be able to explain why in terms of Ionisation Energy and Electronic structure. ]] You should also be able to explain why the elements become less reactive and easier to melt as you go down the group in slightly more detail than you would have done at GCSE. You must be able to write the full electronic structure of the first three Group I '''metals. You should be able to write an equation for their reactions with Oxygen 'and '''Water '''and show that these are 'Redox reactions. The flame test colours (Li = Red, Na = Yellow, K = Purple) are still vaguely relevant. As is the reaction between Group I metals and Halogens. You should also understand that being "good at losing electrons" ''means Alkali metals are "good at" pushing electrons onto other substances - thereby reducing them. This means Alkali Metals are good 'Reducing Agents.' Exam Hints :::'Explain the trend in reactivity down Group I''' At GCSE you learned that Potassium reacts more quickly than Lithium because its outer (valence) electron is more difficult to lose because it is further from the nucleus and so more strongly attracted. This is true but you should now add an argument about Shielding. Lithium's outer electron is barely shielded from the attraction of the nucleus at all. Potassium has rather more inner shells to shield it and so this helps to weaken the attraction of the nucleus. :::Write an equation for the reaction between Rubidium and Oxygen. Explain why this is a '''Redox reaction.' ::::::::'4 Rb(s) + O2 (g) > 2 Rb2O (s) ' 'Oxidation Numberof Rb metal = 0 (element). Oxidation Number of Rb in Rubidium Oxide = +1 An increase in Oxidation Number is '''Oxidation Oxidation Number'of Oxygen gas = 0 (element). Oxidation Number of O in Rubidium Oxide = -2 A decrease in Oxidation Number is 'Reduction {This is what an examiner would expect you to write but you can still explain Redox in O.I.L.R.I.G. terms: Rb > Rb+ + electron - etc} :::Write an equation for the reaction between Lithium and Water. Explain why this is a '''Redox reaction.' ::::::::'2 Li(s) + 2 H2O(l) > 2 LiOH(aq) + H2 (g)' 'Oxidation Numberof Li metal = 0 (element). Oxidation Number of Li in Lithium Hydroxide = +1 An increase in Oxidation Number is '''Oxidation {This is what an examiner would expect you to write but you can still explain Redox in O.I.L.R.I.G. terms: Li > Li+ + electron - } Oxidation Number'of Hydrogen in water= = +1 Oxidation Number of H in Hydrogen gas = 0 (element) A decrease in Oxidation Number is 'Reduction :::Write an equation for the reaction between Sodium and Fluorine. Explain why this is a '''Redox reaction.' ::::::::'2 Na(s) + F2O(g) > 2 NaF(s) ' 'Oxidation Numberof Na metal = 0 (element). Oxidation Number of Na in NaF = +1 An increase in Oxidation Number is '''Oxidation {This is what an examiner would expect you to write but you can still explain Redox in O.I.L.R.I.G. terms: Na > Na+ + electron - } Oxidation Number'of Fluorine gas = = 0 (element). Oxidation Number of F in NaF = -1 A decrease in Oxidation Number is 'Reduction Category:Periodicity